|Roll High or Die.|
This builds into the game an onus on the players to think problems through and create plausible solutions in the hopes that they can avoid the roll altogether.
Into the Odd is built around the same philosophy, but Saves are flat roll-under d20 versus 3d6 stats. Players with high stats don't need to be so motivated to think things through—they can just muscle through.
So: point to Maze Rats.
But Into the Odd has a combat system that I enjoy much more. Hit Points are an abstract defensive reserve to avoid serious injury. Once you're out of hp, you lose STR, and every time you lose STR you need to roll against it to see if you're out of action/ seriously wounded/dying.
This creates a world where anyone needs to fear a knife between the ribs.
I've been wanting to combine these two mechanics, so I thought I'd try emulating the odds of the Danger Roll with the ItO Saves. Here's what that looks like:
2d6 ≥ 10: 16.7%
1d20 equivalent: 3 (15%) or 4 (20%)
1d20 equivalent: 5 (25%) or 6 (30%)
1d20 equivalent: 8 (40%) or 9 (45%)
Imagine starting chargen by telling the players to distribute a 3, 6, and 9 to their stats. That would be so dispiriting!
Advantaged 2d6: 35.7 1d20 equivalent: 7 (35%)
Advantaged 2d6+1: 52.3 1d20 equivalent: 10 (50%)
Advantaged 2d6+2: 68 1d20 equivalent: 14 (70%)
Skills make it better. 7, 10, and 14 don't sound so hopeless.
While I'm at it, here's the numbers for attacking someone without armor in Maze Rats:
2d6: 58.3% 1d20 equivalent: 12 (60%)
2d6+1: 72.2 1d20 equivalent: 14 (70%)
2d6+2: 83.3 1d20 equivalent: 17 (85%)
In most games, it makes sense for attacks to fail more often than ability or skill checks, because you get to try many times to attack, but only once at a given task. In Maze Rats, the opposite holds true, since rolling a Save means you've already failed at the primary mechanic of narrative description.
Anyway, looking at the numbers, my plan to marry the two systems won't work.
Firstly, because of bad optics: the bell-curve of 2d6 looks more forgiving, and +1 or +2 bonus feels positive. A character with stats of 3, 6, and 9 feels hopeless, no matter how many times the GM assures you that these numbers are used differently than D&D stats.
Secondly, because a STR of 3 gives you such a small ability to sustain damage that you lose the benefits of ItO's critical damage system.
But interesting observation to come out of this: the straight up Danger Roll is more or less in the neighborhood of the Old School D&D Saving Throw. It's also in the neighborhood of the Thief Skills. If nothing else, this exercise has convinced me that D&D Thief abilities should be handled descriptively first, and then rolled when that fails.